Duplex telegraph system



May 29, 3923. 1,456,556 E. A. HUDSON DUPLEX TELEGRAPH SYS TEM Filed Dec. 29, 1921 INVENTOR Wg ATTORNEY so sociated wit Patented May 22 EARL A. HUB-Stilt", GF EROQKLYN, NEW YORK, ASSEGNDE TO MEERECMX TELEPEQEGE AW TELEGRAPH COMPANY, A GQRPORATZON F NEW DUPLEX TELEGRAPH SYSTEM.

Application filed December 29, 1921. erial No. 525,598.

To all whom it may concern:

Be it known that l, EARL. A. HUDSON residin at Brooklyn, in the county of Kings and tate of New York, have invented cer- 5 tain Improvementsin Duplex Telegraph Systems, of which the following is a specification.

This invention relates toduplex telegraph systems and the arrangements are suitable both for full duplex operation and half duplex operation. One-of the cardinal features of the invention consists in utilizing polarized relays for the control and pole changerv relays, which .in former arrangements were of theneutral type. The arrangements of the "invention accordingly permit the use of one type of relay throughout each duplex set in place of several different types used in former sets. Such 0 standardization of equipment afi'ords the advantage of greater interchangeability of equipment in theduplexset. Furthermore the arrangements of the invention giye 1mproved operating features and make it possible to eliminate certain of the supplementa'ry contact springs of former duplex relay arrangements. Other features and advantages of the invention will appear more fully from the detailed description hereinafter given.

The invention ma be more fully understood from the fol owing description together with the accompanying drawing in the Figures 1 and 2 of which are 1llustrated the arrangements of the invention as applied to aline suitable for half duplex and for full duplex operation respectively. Similar reference characters have been utilized to denote like parts in both figures.

In Fig. 1 is shown a line L terminating in a set suitable for half duplex operation. Line L is associated with the usual branched windings 5 and the balancing artificial line AL and there is associated therewith in the usual manner the polar line relay 1 including the marking and spacing contacts M.

and S. The line relay responds to the incoming signals from lineL but not to the outgoing signals. The windings 5 are asthe sounder S and with the marking and spacing contacts M and S of the polarized pole changer relay 3] With these contacts are associated the oppositely poled batteries B and B Relay 3 has three windings, a, b,and c. Winding a is included in a local loop circuit comprising battery B winding (1, key K markin contact M of the control relay 2, soun er S sounder S to key K of the substation set X, to ground. The current in windin it tends to hold the armature of rela 3 on its marking contact M as shown. W inding b is included in a local circuit with batter B and the current therein tends to hold t e armature on the spacing contact S. Winding o is included in a circuit with battery B and is controlled by the contacts of relay 1. This winding is known as a holdin. winding and tends to hold the armature o relay 1 on its marking contact when current is removed from the marking winding a b openin the loop circuit at the contact of the contrrfi lay l which would take place when the incoming signals-operate relay 1 aswillbe pointed out later. Relay 2 is the control relay and includes the windings a and b which, are difierentially arranged for purposes which will be pointed out later. Re lay 2 is also a polarized relay.

The arrangements of Fig. I operate in the following manner. It is assumed that similar equipment is connected to the distant end of line L and that a marking current is flowing through line relay 1. This marking current holds the armature of relay 1 on its marking contact M. Current then flows from battery B through contact M, the armature circuit of relay 1, windin a of relay 2, to ground. No current at t is time flows through winding 6 of relay 2 and winding 0 of relay 3, as both ends of the circuit through these windings are connected to the same side of battery 5 The current through winding a: of relay 2 will now hold the armature of said relay on its marking contact M closing the circuit from battery B through winding a of relay 3, key K contact Mot relay 2, sounder S and telegraph set at substation X, which includes sounder S and key K This current keeps the armature of relay 3 closed on its contact M. Sounder S at the duplex set and sounder S; at the substation X are closed indicating to the operator at both. points that a marking signal is being received.

en a spacing signal 1s received from line L, it moves the armature of relay 1 from its contact M to contact S. While the armature is passing between these contacts, current flows from battery 13,, through conductor 4, winding 0 of relay 3, and windings Z) and a of relay 2, to ground. This current in winding 0 of relay 3 helps to hold the armature thereof on contact M, but in relay 2 windings b and 0; are opposing and have no eliect upon the armature; consequently it remains on its contact M during this interval. When the armature of relay 1 reaches con tact 8, current is diverted from winding a of relay 2 by the short circuit to ground through said contact 8 of relay 1, and the current inwinding 0 of relay 3 is somewhat increased by the removal of winding a of relay 2 from the circuit, This current holds the armature of relay 3 on contact M and moves the armature of relay 2 from contact M to contact S. Opening contact M of relay 2 removes current from winding A of relay 3 and from Sounders S, and 3,. No change occurs at relay 3, as current in winding 0 still holds its armature on contact M, but sounders S and S, are released, indicating to the operators at the duplex set and the substation that a spacing signal is being received.

When an incoming marking signal from line L again moves the armature of relay 1 to its marking contact M, the conditions first noted above are restored. However, While the armature of relay 1 is moving from the spacing to the marking contact, current flows through winding 0 of relay 3 and through windings]; and a of relay 2. This current in relay 3 holds its armature on the marking contact, but in relay 2 it produces no efi'ect, as windings a and bare opposing. The armature of relay 2 is therefore not moved to its marking contact until the marking contact of relay 1 closes.

If, when the circuits are normally closed, as shown in Fig, 1, either of the keys K, or K, in the local loop circuit are opened to transmit a spacing signal, current will cease to flow in winding A of relay 3., Thereupon the current which continually flows 'from battery B, through winding 1) will move the armature to the spacing contact a. A. spacing signal will then be transmitted to the line. A small portion of this spacingcun -rent flows through sounder S causing it to release, and the balance of the current divides at the apex of the windings 5, equal parts flowing through line L and artificial 1 line AL in the usual manner and having no Closing the key restores effect upon relay 1. current to winding a of relay 3, and moves its armature to contact M, thus transmitting a marking signal, and closing sounder S Thus signals passing over the line operate similar equipment at the distant end of the line to reproduce the signals in the same ,lay for short circuiting one o intense manner as described above. It is one of the functions of sounder S toindicate to the operator at the duplex set that signals are being properly transmitted. Sounder S is also polarized,

It is a further function of sounder S to control the operation of the break which is a necessary feature of half duplex opera tion. When the operator opens the local loop circuit to give the break signal to get control of the line from the distant operator, the spacing current will operate sounder 8,. When the break signal being transmitted it is necessary to prevent the incoming spacing signals which would operate the 'line relay from operating and opening the control relay which in turn would tend to lock the pole changer. This is accomplished by closing at the back'contact of sounder S, a short circuit about the pole changer holding winding 0 and the control relay opening winding Z). With this arrangement the operation of the line relay by an incoming spacing signal cannot then interrupt the break signal.

In Fig. 2 the arrangements of the invention are shown in a set adapted for full duplex operation. Similar reference characters have been used to denote like parts with respect to Fig. 1, Fig. 2 is substantially similar to Fig. 1 except that winding 0 of the pole changer relay 3 is inoperative and is not connected to winding 6 of control relay 2. Furthermore winding 6 of relay 2 is connected to battery B in a slightly difierent manner than before. The principles of operation however are substantially similar to those already described and no further description thereof will be given.

While the invention has been disclosed in certain specific arrangements which are lay having marking and spacing windings differentially arranged, a circuit normally including in series both of the windings of said control relay and the holding windas defined in the aping of said pole changer rela and means controlled by the operation 0 aid'line re ings of said control relay. I

2. Aduplex telegraph set comprising a polarized line relay, having marking and the wind- I spacing contacts, a polarized pole changer relay having marking, spacing and holding windings, a polarized control relay having marking and spacing windings difiae inseam ferentially arranged, a circuit including .in series both of the windings of said control relay and the holding winding of, said pole changer relay, and means for short circuiting it e marking winding of said control -relay over the spacing contact of said line relay.

3. A duplex telegraph set comprising a polarized line relay, a polarized polechanger relay having marking, spacing, and holding windings, a polarized control relay having marking and spacing windings differentially arranged, a circuit including in series both of the windings of said control relay and the holding winding of said pole changer relay, means for controlling said circuit over the contacts of said line relay, and means controlled by said pole changer relay for closing a short circuit across first circuit between said relay windings and the contacts of said line relay.

4. A duplex telegraph set comprising a polarized line relay, a polarized pole changer relay having marking, spacing and holding windings, a polarized control relay having marking and spacing windings differentially arranged, a circuit normally including in series 'both of the windings of said control relay and the holding winding of said pole changer relay, and, means controlled over the marking contact of said line relayv for short circuiting said holding winding of said pole changer and one Winding of said control relay.

In testimony whereof, I have signed my name to this specification this 28th day of December, 1921.

EARL A. HUDSON. 

